let header = document.querySelector('.header')
// header.addEventListener('')
window.addEventListener('scroll', () => {
  var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
  // console.log("滚动距离" + scrollTop);
  if (scrollTop > 80) {
    header.className = 'header up'
  }
  if (scrollTop <= 80) {
    header.className = 'header'
  }
})
var windowWidth = window.innerWidth;
var windowHeight = window.innerHeight;

console.log("浏览器窗口宽度：" + windowWidth);
console.log("浏览器窗口高度：" + windowHeight);